Question

I have a web server (ASP.NET – Mono 2.6.7) with a value static float x in it and two methods : getX() and setX(newX). I also have two clients one is a pc with c# console application and the other one is a mobile device with android (ksoap2). Both can access the web server.

What I do not know is : if my mobile device try to do a getX() while my pc is doing a setX(newX), will it result any trouble ?

Thanks.

Answer 1

It’s not a good practice to have a state-full implementation for services. You can have different instances serving multiple requests. This is the case in ASP.NET web services. In WCF, using configuration, you can change instancing behavior. For example, you can have a single instance serving all requests (few of them can be concurrent) – in case, one has mutable state (as in your case), you have to synchronize the access to the state. Thread synchronization on shared state will create a bottleneck in serving the requests because at the most only one request thread can access the state. Further, you cannot scale horizontally (i.e. web farm scenario where requests will be served from multiple machines). If you choose to have multiple instances serving the request then you need to externalize the state e.g. put it into the database. In such case, you will incur in the penalty of accessing external data source (which can be much higher than thread synchronization) but you will have scalable design.